Musical instrument bearing insert



1969 w. D. WHITESIDE ETAL 3,421,398

MUSICAL INSTRUMENT BEARING INSERT Filed Oct. 1, 1965 04-Ma wzdwag United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE A plastic bearing insert between a square ended hinge rod and a cylindrical headed hinge post on a clarinet or the like, the bearing insert having a flat end and a concave end' adapting to the confronting surfaces.

This invention relates to the mounting of keys and the like on musical wind instruments, and more particularly to a bearing insert for such a wind instrument.

In the manufacture of musical wind instruments, such as clarinets and Saxophones, it is common practice to provide posts having pivot rods extending therebetween with sleeves pivoted thereon to which the various keys and levers are soldered or brazed. It is imperative that the tubes be free to pivot freely so as not to produce malfunctions and playing of false notes, nor to inhibit fingering of the instrument by the player. Unfortunately, such difficulties have been encountered too frequently in the past.

In order that the tubes might properly interfi-t with the posts it heretofore has been common practice to grind the spherical heads of the posts flat on the faces engaging the tubes. It is imperative that the faces be ground fiat absolutely perpendicular to the axis of the rods and tubes extending therebetween, and this is extremely difficult to do, particularly in the case of instruments having tapered bodies, such as Saxophones. Extreme precision and care have been necessary, thus making for an expensive production step.

Another problem frequently encountered with the post and tube construction is that the tubes and instrument bodies may not expand and contract thermally at the same rate. For example, the tubes are uniformly made of metal, While the bodies of many wind instruments, such as clarinets, are made of wood or plastic. Generally speaking, the metal expands and contracts more with temperature than does the Wood, while the wood expands and contracts more with the moisture content than does the metal which is substantially unaffected dimensionally by moisture. This has often caused binding of the tubes so that they have not pivoted freely.

- It is an object of the present invention to provide means for mounting pivot tubes on posts that simultaneously eliminates the face machining step on the posts and prevents binding with thermal and moisture changes in dimensions.

A further object of the present invention is to eliminate the post face machining operation noted heretofore and to prevent binding of tubes hinged between posts by meansof a novel bearing insert.

More particularly, it is an object of this invention to 3,421,398 Patented Jan. 14, 1969 ice provide a plastic or other resilient bearing insert spherically concave on one face for interfitting with a post head and fiat on the other side for interfitting with the hinge tube, and due to its resiliency preventing binding upon differential expansion of the parts.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a portion of a musical instrument incorporating the pivot post mounting of the present invention;

FIG. 2 is a side view of the hinge tube and associated parts of FIG. 1 being taken substantially in axial section relative to the instrument;

FIG. 3 is an enlarged view similar to a portion of FIG. 2 and with certain parts thereof shown in crosssection;

FIG. 4 is a cross-sectional view as taken substantially along the line 44 in FIG. 3; and

FIG. 5 is a perspective view of the plastic bearing insert forming the major subject matter of the present invention.

Referring now in greater particularity to the drawings, there is shown a portion of a tubular body 10 of a musical wind instrument 12. The body may be made of metal, wood, or plastic in accordance with conventional practice. The body is provided with a pair of longitudinally spaced posts 14, each having a cylindrical head 16 in accordance with conventional practice. In accordance with prior pratice, it has been customary to machine fiat faces in confronting relation on the cylindrical heads, such faces being absolutely perpendicular to a straight line or axis between the centers of the heads. This is dispensed with in accordance with the present invention. Instead, the heads are left in their original, spherical condition or shape.

The post mentioned above may be mounted on the body 10 in conventional manner, as by abrasing in the case of a metal body or by screws or screw threads in wooden or plastic bodies.

A metal hinge rod 18 extends between the posts 14. The hinge rod in accordance with conventional practice, comprises an elongated cylindrical rod of uniform diameter throughout most of its length and extending through .a complementary bore 20 in one of the posts, for example the right post as shown in FIG. 2. At the opposite end the hinge rod is provided with a portion of restricted length having a reduced diameter and provided with screw threads 22 thereon. This screw threaded end is threadedly received in a complementary bore 24 in the head of the corresponding post, i.e., the left post in the illustrative example. Ideally, the bores 20 and 24 are aligned, but as a practical matter this is not quite necessary since the parts will give sufficiently to allow the hinge rod to be associated with the posts, it being borne in mind that the hinge rod or pivot rod does not move relative to the posts following installation. As will be apparent, 'in accordance with conventional practice the end of the hinge rod opposite the threaded end is provided with a cross slot or other driving means for screwing the hinge rod into place.

A metal hinge tube 26 is pivotally mounted on the hinge rod 18. The internal diameter of the tube is only very slightly greater than the outside diameter of the rod so asto pivot freely thereon without rattling. In accordance with conventional practice the hinge tube extends into engagement at either end with the adjacent posts, and specifically the fiat faces thereof, the hinge tube having squared off or right-angle ends 28. In the present instance the hinge tube is terminated short of the posts as will be brought out shortly hereinafter.

The hinge tube has a key lever 30 extending from one portion thereof in a lateral direction, the outer end of the key lever being provided with a finger piece or spatula 32. A lever 34 extends from the hinge tube 26 and is shown as extending in the opposite direction, carrying at its outer end a key cup 36 having a pad (not shown) for selectively closing the hole (not shown) in the instrument body in accordance with the manipulation of the spatula or finger piece 32. As will be understood, a suitable spring is provided for biasing the tube rotationally in the desired direction.

The distinction of the present construction over the prior art, and wherein lies the heart of the invention, is in the provision of a plastic bearing insert 38, or, more specifically two such plastic bearing inserts, one at each end of the hinge tube 26. Nylon is one plastic material that has been found to be satisfactory, although other materials are also useful. The plastic material must be reasonably dimensionally stable with changes in temperature and humidity, it must be resilient, resistant to wear, and have low frictional qualities in engagement with metal parts. Each bearing insert 38 is in the nature of a generally cylindrical member or button having an outside diameter preferably just slightly greater than the diameter of the adjacent hinge tube. For example, a typical hinge tube outside diameter is .188", while the corresponding outside diameter of the bearing insert 38 is .193. Typically, also the maximum length of the bearing insert is .045. The lengths of the two bearing inserts together are just sufiicient to hold the hinge tube 26 between them without rattling or shaking around, and yet free for ready pivoting without binding.

Each bearing insert 38 is fiat on one face as at 40, perpendicular to the axis thereof. The opposite face is concave or semi-spherical as indicated at 42. This face engages the spherical head of the corresponding post 14, and is movable thereabout to insure proper alignment of the bearing insert 38 relative to the adjacent tube 26 and hinge rod 18, the bearing insert face 40 fitting flush against the end or face 28 of the tube. A significant feature of the concave face 42 of the bearing insert is that it has a very slightly lesser radius than that of the corresponding spherical head 16. For example, a typical spherical head radius is .156". The cor-responding concave surface 42 of the hearing insert is .150. Thus, theoretically, the hearing insert would engage only on a circular line with the head. However, only a very slight axial force is required to distort the hearing insert sufiiciently that there is substantially surface engagement between the head and the bearing insert. As will be apparent, axial stress such as might be developed through differential expansion of the parts, might tend to cause engagement between a bearing insert and an adjacent post head to become less of a surface engagement if there initially were perfect surface engagement, or if the radius of concavity of the bearing insert were slightly greater than that of the post head.

It will be understood that if a hinge tube is slightly short relative to the spacing between posts it is a simple matter to use slightly over-long bearing inserts to take up any play. Conversely, should the space in between posts decrease relative to the length of a hinge tube, then the corresponding bearing inserts would simply compress slightly, thereby taking up the difference without binding of the hinge tube.

Facing of the post heads, and also of the confronting ends of the hinge tubes is completely eliminated. The spherical concave surface of the bearing insert contacts the head of the post in substantially perfect surface engagement, and there is an appearance of a perfect facing without the necessity of any facing operation. With proper choice of plastic materials little or no lubrication is necessary. Obviously, there can be no rattling of the mechanism.

Since the post heads are not faced, a longer diameter is left for engagement by the screw threads of the hinge rod. This allows a more secure mounting and makes the conventional nylon thread locking arrangement used therewith more effective. There is little or no need for deburring of either the post or the hinge tubes in accordance with the present invention. As will be appreciated, when a post head has been faced, there is a necessity of bufling the faces, and such bufiing tends to round off, and hence reduce the facing. In the present invention there is no problem of rounding off, since there is no facing.

The material from which the bearing insert is made can be dyed a suitable color to provide an ornamental appearance, preferably contrasting with that of the musical instrument on which the bearing insertsare used.

The axial bore 44 through each bearing is substantially the same diameter as the bores through the hinge tube 26, but it will be apparent that precise dimensioning at this point is not critical, since there are radial forces as well as axial forces tending properly to position each bearing insert.

It will be understood that the specific example of the invention as herein shown and described is for illustrative purposes. Various changes in structure will no doubt occur to those skilled in the art, and such changes will be understood as forming a part of the present invention insofar as they fall within the spirit and scope of the appended claims.

The invention is claimed as follows:

1. In a musical wind instrument having a hollow body with a pair of spaced metal posts thereon and a metal pivot member having a squared-off end extending between said posts and pivotally supported thereby, said posts having substantially spherical heads, said pivot member comprising a hollow sleeve having said squared-0tf end and a hinge rod extending through said sleeve and screwthreadedly connected to at least one of said posts, a bearing insert between said pivot squared-off end and an adjacent post, said bearing insert having a concave surface substantially complementary to a post head and an opposite surface substantially flat and complementary to said pivot member, said bearing insert comprising a resilient plastic material interposed between a squared-off sleeve end and a spherical post head.

2. In a musical wind instrument having a hollow body with a pair of spaced metal posts thereon and a metal pivot member having a squared-01f end extending between said posts and pivotally supported thereby, said posts having substantially spherical heads, a bearing insert between said pivot mem ber squared-off end and an adjacent post, said bearing insert having a concave surface substantially complementary to a post head and an opposite substantially flat surface substantially complementary to said pivot member, said bearing insert comprising a resilient plastic material.

3. In a musical wind instrument having a hollow body with a pair of spaced metal posts thereon and a metal pivot member having a squared-off end extending between said posts and pivotally supported thereby, said posts having substantially spherical heads, a resilient plastic bearing insert between said pivot member squared-01f end and an adjacent post, said bearing insert having a concave surface substantially complementary to a post head and an opposite substantially fiat surface substantially complementary to said pivot member, said bearing insert concave surface comprising a spherical segment having a radius of curvature less than the radius of our vature of the confronting post head.

(References on following page) References Cited UNITED STATES PATENTS Gilmore 308-140 Rowlett 308-238 Donnellan 308-238 Shaw 84-380 Silver 84-380 Sutowski 308-238 6 3,011,219 12/1961 Williams 18-59 3,065,035 11/1962 Biesecker 308-15 RICHARD B. WILKINSON, Primary Examiner.

5 L. R. FRANKLIN, Assistant Examiner.

U.S. Cl. X.R. 

